APOE4 cell-specific mechanisms underlying cerebrovascular disorder precede neuronal and synaptic dysfunction and cognitive deficits in mice
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE185063 | GEO | 2022/08/22
REPOSITORIES: GEO
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Project description:Apolipoprotein E4 (APOE4), the main susceptibly gene for Alzheimer’s disease1–5, exerts cerebrovascular toxicity6 leading to blood-brain barrier (BBB) breakdown in humans7–9 and APOE4 transgenic mice10–13. Moreover, an early BBB dysfunction predicts cognitive decline in humans7. However, the comprehensive large-scale analysis of cell-specific mechanisms underlying APOE4 cerebrovascular disorder and how it relates to neuronal disorder is lacking. Using single-nucleus RNA-sequencing, phosphoproteome and proteome analysis14–17 here we show that APOE4 compared to APOE3 leads to early disruption of the BBB transcriptome in 2-3-month old APOE4 knock-in mice18 followed by dysregulation in protein signaling networks. This includes proteins regulating cell junctions, cytoskeleton, clathrin-mediated transport, and translation in brain endothelium, and transcription and RNA-splicing suggestive of DNA damage in pericytes. Changes in the BBB signaling mechanisms paralleled an early, progressive BBB breakdown and loss of pericytes starting at 2-3 months of age. The BBB breakdown preceded loss of neurites, post-synaptic interactome dysregulation, and behavioral deficits that developed 2-5 months later, and was associated with astrocyte and microglia response protecting BBB integrity. Thus, disruption of the BBB cell-specific signaling mechanisms could be an initial central contributor to APOE4-mediated neuronal disorder, and possibly a major target to correct APOE4-related cognitive deficits.
2022-08-23 | PXD029230 | Pride
Project description:The apolipoprotein E4 (APOE4) gene is the strongest genetic risk factor for late-onset Alzheimer’s disease (AD). ApoE is a lipid carrier abundantly expressed in both brain and periphery. As peripheral apoE is separated from brain apoE by the blood-brain barrier, it remains unclear whether peripheral apoE impacts brain functions and AD pathogenesis. To investigate this, we developed novel mouse models that conditionally express human APOE3 or APOE4 only in the liver with no detectable apoE in the brain. We found that liver-expressed apoE4 compromised synaptic plasticity and cognitive behaviors likely by impairing cerebrovascular functions. Remarkably, liver-expressed apoE4 exacerbated brain amyloid pathology, whereas apoE3 reduced it. Our findings demonstrate a pathogenic effect of peripheral apoE4, providing strong rationale for targeting peripheral apoE to treat AD.
2022-06-15 | GSE125501 | GEO
Project description:The aim of the study was to investigate hepatic gene expression profiles differentially regulated by the APOE genotype in gene targeted replacement mice. The APOE4 genotype is associated with increased mortality in the elderly and is an independent risk factor for age-dependent chronic diseases. However, little is known about the underlying mechanisms and molecular targets involved in the APOE4-risk association. As APOE is centrally involved in lipid and cholesterol metabolism and in large part is produced in the liver, we analyzed hepatic RNA profiles of APOE4- and APOE3-expressing mice. 2 groups of 5 animals with 1 liver extract per animal. Mice were homozygous for a human APOE3 or APOE4 gene targeted replacement of the endogenous mouse Apoe gene (B6.129P2-Apoetm2(APOE*3)Mae N8 or B6.129P2-Apoetm3(APOE*4)Mae N8, Taconic Transgenic ModelsM-bM-^DM-", http://www.taconic.com/wmspage.cfm?parm1=2542), purchased at the age of 6-8 weeks, strain C57BL/6, 3 months old at the performance of the microarray, 6 weeks on a high-fat diet containing 41% energy from milk fat and 2 g/kg cholesterol.
2012-12-15 | E-GEOD-42930 | biostudies-arrayexpress
Project description:We used bulk RNA sequencing to investigate the molecular signature of phagocytic and non-phagocytic microglia affected by APOE isoform (APOE3-KI vs. APOE3-cKO vs. APOE4-KI vs. APOE4-cKO)
2023-07-31 | GSE234350 | GEO
Project description:The majority of Alzheimer’s disease patients and 20–40% of non-demented elderly experience amyloid deposits along their cerebral vasculature, a condition known as cerebral amyloid angiopathy (CAA). CAA impairs the function of the blood-brain barrier (BBB) leading to ischemia, hemorrhages, and accelerated cognitive dysfunction. The APOE4 allele is the strongest known genetic risk factor for CAA and sporadic AD, however the pathogenic mechanisms underlying this predisposition are unknown. Here, we recreate the human BBB in vitro by co-culturing the three cellular components of the BBB, endothelial cells, pericytes, and astrocytes in 3D scaffolding to construct a tractable model that recapitulates key anatomical and physiological properties of the BBB. Similar to the in vivo BBB, we find amyloid accumulates on our in vitro BBB (iBBB) and both APOE4 homozygous and heterozygous iBBBs exhibit significantly more amyloid accumulation than APOE3/3 iBBBs. Combinatorial experiments revealed that pericytes have a causal role in the development of CAA. We found that APOE expression is markedly up-regulated in APOE4 pericytes, but not in astrocytes or endothelial cells. Transcriptional profiling revealed that calcineurin/NFAT signaling is dysregulated in APOE4 pericytes. Pharmacologically inhibiting calcineurin led to downregulation of APOE and subsequently reduced amyloid deposition on the iBBB. These results demonstrate an unexpected role of pericytes in cerebral amyloid deposition and advocate for inhibiting calcineurin/NFAT-signaling as a therapeutic strategy to mitigate APOE4 predisposition to CAA and potentially AD.
2019-07-31 | GSE125869 | GEO
Project description:APOE4 genotype is the strongest risk factor for the pathogenesis of sporadic Alzheimer’s disease (AD), but the detailed molecular mechanism of APOE4-mediated synaptic impairment remains to be determined in human cellular context. In this study, we generated human astrocyte model carrying APOE3 or APOE4 genotype using human induced pluripotent stem cells (iPSCs), in which isogenic APOE4 iPSCs were genome-edited from healthy control APOE3 iPSCs. By transcriptome analysis of human astrocytes between APOE genotypes, we showed the upregulation of an extracellular matrix glycoprotein in human APOE4 astrocytes, which may cause synaptic degeneration in concert with the equivocal reactive character and lipid change. Together, these results demonstrate novel negative impact of human APOE4 astrocyte on synaptic integrity and lead to a promising therapeutic intervention into APOE4-carriers.
2023-08-31 | GSE206314 | GEO
Project description:We used bulk RNA sequencing to investigate the molecular signature of phagocytic and non-phagocytic microglia affected by APOE isoform (APOE3-KI vs. APOE4-KI)
2023-07-31 | GSE234348 | GEO
Project description:The development of treatment for Alzheimer’s Disease (AD) is hindered by a limited understanding of its structural basis. Apolipoprotein E (APOE) ε4 genotype is the most important risk factor for late-onset AD. APOE4 differs from the APOE3 isoform by a single mutation, C112R. Here, we employ crystallography, biophysical methods and computer simulations to dissect the “domino-like” effect of C112R substitution on APOE4 behaviour. We found that the mutation induces long-distance (>15 Å) conformational changes leading to geometrically distinct T-shaped dimeric unit of APOE4 compared to APOE3. By mutagenesis, we demonstrate that the APOE4 unit is more prone to aggregation than that of the APOE3. AD drug candidate tramiprosate and metabolite 3-sulfopropanoic acid induce APOE3-like conformational behaviour in APOE4 and suppress its aggregation propensity. Omics analysis of APOE ε4/ε4 cerebral organoids treated with tramiprosate revealed its effect on cholesteryl esters, the storage product of excess cholesterol. Our results connect the APOE4 structure with its aggregation propensity, which can be further exploited in drug development for neurodegeneration and ageing.
2023-07-20 | PXD036416 | Pride
Project description:Cells in the cortex of mice expressing apoE3 or apoE4 in the microglia were isolated and subjected to the single-cell RNA seq to investigate the effects of microglia/CNS-associated macrophages (CAMs) apoE on the brain transcriptomic profiles. Our data revealed that microglia/CAM-expressed apoE3 promotes antigen presentation and immune patnways, whereas apoE4 down-regulates complement and promotes stress-related responses.
2023-11-02 | GSE241553 | GEO
Project description:Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer’s Disease (AD). While neurons generally produce a minority of the apoE in the central nervous system, neuronal expression of apoE increases dramatically in response to stress and is sufficient to drive pathology. Currently, the molecular mechanisms of how apoE4 expression may regulate pathology are not fully understood. Here we expand upon our previous studies measuring the impact of apoE4 on protein abundance to include the analysis of protein phosphorylation and ubiquitylation signaling in isogenic Neuro-2a cells expressing apoE3 or apoE4. We find that apoE4 expression results in the dramatic increase in VASP S235 phosphorylation in a PKA-dependent manner. This phosphorylation results in the loss of VASP interactions with numerous actin cytoskeletal and microtubular proteins. Reduction of VASP S235 phosphorylation via PKA inhibition results in a significant increase in filopodia formation and neurite outgrowth in apoE4-expressing cells to levels beyond that of apoE3. Our results highlight the pronounced and diverse impact of apoE4 on multiple modes of protein regulation and identify potential therapeutic targets to restore apoE4-related cytoskeletal defects.
2023-04-08 | PXD041205 | Pride